Learn to find and configure what displays on your Lightroom Toolbars
The toolbar which appears between the Filmstrip and the Loupe or Grid views can be configured to display a range of options. Click the down pointing arrow to choose which items to display on the toolbar from the popup menu. This is particularly useful when you are working on a laptop because there isn’t a lot of screen space. Also be aware that the toolbars for the Loupe and Grid views are different so you can set each independently of each other.
And, if your toolbar isn’t visible? Press T to toggle its visibility on and off.